Conventionally, for example in a field of manufacturing semiconductor units, with respect to many semiconductor devices formed on a semiconductor wafer, before the semiconductor wafer is cut and divided, an electric characteristic of each of the many semiconductor devices is measured to examine whether it is defective or not. A probe apparatus is used for the examination.
A wafer-stage that can hold a semiconductor wafer is provided in the probe apparatus. The wafer-stage is provided with a driving mechanism, which includes an X-Y drive mechanism such as an X-Y table and a Z-axis drive mechanism or the like. By means of the driving mechanism, a semiconductor wafer held on the wafer-stage can be moved in X-Y-Z directions.
A probe-card holding mechanism is provided above the wafer-stage for holding a probe card provided with many probe needles correspondingly to electrode pads of semiconductor devices.
Then, a predetermined probe card is held by the above probe-card holding mechanism. A semiconductor wafer, whose electric characteristic is to be examined, is arranged on the wafer-stage. Then, by moving the wafer-stage in the X-Y-Z directions, the group of probe needles is moved at a predetermined movement pitch relatively to the plurality of groups of electrode pads, so that the former comes in contact with the latter successively. Thus, by means of testers electrically connected to the group of probe needles, it is examined whether an electric characteristic of each semiconductor device is good or not.
As described above, in the conventional probe apparatus, by the wafer-stage being moved, the group of probe needles comes in contact with the plurality of groups of electrode pads, successively. The movement of the wafer-stage is carried out step by step. That is, the movement and stop of the wafer-stage is repeated at the predetermined pitch. While the wafer-stage is stopped, an electric characteristic of each semiconductor device is examined.
However, when the wafer-stage is stopped after it is moved, mechanical vibrations caused by moving and stopping the wafer-stage may remain in respective components of the probe apparatus. Because of the mechanical vibrations, the contact state between a group of electrode pads and the group of probe needles may become unstable, which may make it impossible to favorably measure the electric characteristic.
In order to solve the above problems, the above measurement may be carried out after a predetermined delay time after the wafer-stage is stopped. However, if such a delay time becomes long, throughput may be lowered.
In addition, if a vibration is given to a group of electrode pads of semiconductor devices and the group of probe needles when they come in contact with each other, the surfaces of electrode pads may be scratched by the probe needles in an undesired manner so that the surfaces may be damaged.
Furthermore, if the above mechanical vibration is transmitted to a camera or the like used for a positioning operation, focusing thereof may not be achieved. Even if the focusing is achieved, the image of the camera may hobble and thus the positioning operation may not be achieved. Thus, anyway, the positioning operation has to be waited until the vibration is attenuated, which may badly affect the throughput.
Recently, semiconductor wafers have been enlarged to a 12-inch diameter size or the like. Thus, components of the wafer-stage, size of the head plate and so on have been enlarged, and weights thereof have been also increased. Therefore, the problems of the above mechanical vibration tend to be especially significant.